1. Field
Embodiments described herein relate generally to a method of evaluating a semiconductor storage device.
2. Background Art
For example, a semiconductor storage device of a floating gate type EEPROM such as a NAND-type flash memory makes charges pass through a tunnel insulating film and changes the charge amount of a floating gate.
However, if the charges are moved in the tunnel insulating film, the tunnel insulating film is deteriorated (trap is generated). Thereby, the charges are accumulated in the trap that is generated in the tunnel insulating film and a data retention characteristic is deteriorated.
In the conventional art, a charge distribution in the tunnel insulating film cannot be recognized and it is difficult to investigate a quality of the tunnel insulating film or grasp a characteristic of an electron density distribution.